HTML Viewer is a free lightweight local HTML viewer app for Android developed by Shiratori. It allows users to verify HTML and JavaScript files created for smartphones. With this app, users can easily view local HTML files, including those in ZIP format, and view their contents in landscape or portrait orientation. The app also supports CSS files and allows users to scale the browser.

HTML Viewer also features a file explorer in the SD card, allowing users to launch another application with support for notification intent. By default, the app opens the directory "/mnt/sdcard" and users can move up/back key is pressed. The app also displays the updated date of the file and supports extensions such as .htm, .html, .xml, .js, .css, and .json.

Additionally, HTML Viewer comes with two introduction apps: "Text Viewer" and "CSV Viewer." The former is an application that refers to the text file, while the latter is an application to view CSV files. Overall, HTML Viewer is a safe and secure application that provides users with a simple and easy way to view local HTML files on their Android devices.